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Washington (AFP) – Just a week after the first images were shown to the world, the James Webb Space Telescope may have found a galaxy that existed 13.5 billion years ago, said a scientist who analyzed the data on Wednesday.
Known as GLASS-z13, the galaxy dates back 300 million years after the Big Bang, about 100 million years earlier than anything previously identified, Rohan Naidu of the Harvard Center for Astrophysics told AFP.
“We are potentially looking at the farthest starlight anyone has ever seen,” he said.
The more distant objects are from us, the longer it takes for their light to reach us, and to look back into the distant universe is to look into the deep past.
Although GLASS-z13 existed in the earliest epoch of the universe, its exact age remains unknown since it could have formed at any time within the first 300 million years.
GLASS-z13 was discovered in so-called “early release” data from the orbiting observatory’s main infrared camera, called NIRcam – but the discovery was not revealed in the first image set published by NASA last week.
When translated from infrared to the visible spectrum, the galaxy appears as a red lump with white in the center, as part of a broader image of the distant cosmos called a “deep field”.
Naidu and colleagues – a team of a total of 25 astronomers from around the world – have submitted their findings to a scientific journal.
Currently, the research is posted on a “preprint” server, so it comes with the proviso that it has not yet been peer-reviewed – but it has already put the global astronomical community at full speed.
“Astronomical records are already crumbling, and more are shaking,” tweeted NASA chief scientist Thomas Zurbuchen.
“Yes, I tend to only cheer when scientific results have a clear peer review. But this looks very promising,” he added.
Naidu said that another team of astronomers led by Marco Castellano who worked on the same data has reached similar conclusions, “so it gives us confidence.”
‘Jobs to be done’
One of Webb’s great promises is the ability to find the earliest galaxies formed after the Big Bang 13.8 billion years ago.
Because these are so far from the earth, when their light reaches us, it has been stretched by the expansion of the universe and moved to the infrared region of the light spectrum, which Webb is equipped to detect with unparalleled clarity.
Naidu and colleagues combed these infrared data from the distant universe, searching for a revealing signature of extremely distant galaxies.
Below a certain infrared wavelength threshold, all photons – energy packets – are absorbed by the neutral hydrogen in the universe that lies between the object and the observer.
Using data collected through different infrared filters pointed at the same area in space, they were able to detect where these falls in photons occurred, from which they deduced the presence of these most distant galaxies.
“We searched in all the early data for galaxies with this very striking signature, and these were the two systems that had by far the most convincing signature,” Naidu said.
One of these is GLASS-z13, while the other, not as old, is GLASS-z11.
“There is strong evidence, but there is still work to be done,” Naidu said.
In particular, the team wants to ask Web leaders for telescopic time to perform spectroscopy – an analysis of light that reveals detailed properties – to measure its exact distance.
“Right now, our guess for distance is based on what we do not see – it would be great to have an answer to what we see,” Naidu said.
Already, however, the team has discovered surprising properties.
For example, the galaxy is the mass of a billion suns, which is “potentially very surprising, and there is something we do not really understand” given how soon after the Big Bang it was formed, Naidu said.
Launched in December last year and fully operational since last week, the Web is the most powerful space telescope ever built, with astronomers confident it will herald a new era of discovery.
© 2022 AFP